


mr. brightside

by elisela



Series: what's your emergency? [1]
Category: 9-1-1 (TV), Teen Wolf (TV)
Genre: Crossover, Established Relationship (Sterek), Getting Together (Buddie), M/M, idiots to lovers, no beta we die like men
Language: English
Status: Completed
Published: 2020-09-29
Updated: 2020-09-29
Packaged: 2021-03-07 21:35:43
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,255
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/26714581
Author URL: https://archiveofourown.org/users/elisela/pseuds/elisela
Summary: In which Derek joins the 118 and Buck is completely, absolutely jealous, because there's nowayEddie won't fall for the guy. Right?
Relationships: Derek Hale/Stiles Stilinski, Evan "Buck" Buckley/Eddie Diaz (9-1-1 TV)
Series: what's your emergency? [1]
Series URL: https://archiveofourown.org/series/2051928
Comments: 31
Kudos: 643





	mr. brightside

**Author's Note:**

  * For [florenceandthemachine](https://archiveofourown.org/users/florenceandthemachine/gifts).



> So it went something like this:
> 
> Lauren: of course I won't let you start writing Sterek  
> Flo: Let's just pretend that Derek joining the 118 is canon  
> Me: oh fuck
> 
> Five hours later, there was this self-indulgent mess.

“Listen up, underlings,” Chim says, rubbing his hands together with a gleeful expression. Next to Buck, Eddie groans, tipping his head back onto the couch. “Aren’t you supposed to be standing for this? Stand up. Show your Captain some respect.”

Buck flips him a salute—literally, middle finger touching the arch of his eyebrow and snapped sharply out in front of him—but doesn’t move. “ _Interim_ Captain,” he says, knocking his elbow against Eddie’s arm when he brings his hand back down. “Continue.”

Chim gives him a look. “As you know—”

“Are they coming to fix the AC any time soon?” Eddie interrupts, and Buck chokes back a laugh. It’s entirely unlike Eddie to be blatantly disrespectful, even if Chim is only Captain for another week, so he must still be irritated over the whole coffee incident even though Buck had pressed his own cup into Eddie’s hand when it became clear that Chim had forgotten to order Eddie’s extremely boring “coffee, black”. Eddie hadn’t taken it on account of it being “coffee flavored milk” (“That’s what a latte _is_ ,” Buck had protested), but he’d smiled at Buck all the same and had, once again, made Buck go a little weak in the knees. 

“After the departure of our dear Henrietta—”

“Wish it’d been someone else whose name starts with H,” Eddie grumbles, but Buck sees the way the corner of his mouth quirks up into a grin before he stamps it down. 

“—who I desperately wish was here instead of you two oafs—”

“See if I pull your ass out of a burning building, Chim,” Buck says, and Eddie’s knee knocks against his quite intentionally. “We get it, probie’s here, blah blah, best behavior, can we wrap this up yet? I’m starving and there are bagels on the counter.”

“Fine,” Chim says, throwing his hands up. “Introduce yourselves then, try not to have him running for the door in ten seconds. And _you_ ,” he says, pointing at Buck, “don’t get all snippy when he’s hotter than you like you did with Eddie.”

“Eddie’s not _hotter than me_ ,” he protests, and when Eddie makes a noise that sounds distinctly like a dying cat beside him, he adds, “but that’s not—I didn’t think he—oh fuck off,” he says to Chim’s retreating back.

“It’s okay, buddy,” Eddie says, openly laughing, and okay, Buck’s been used to their casual—well, maybe on Eddie’s part—touching for years now, but the way his warm hand squeezes Buck’s knee sends his heart racing. “Come on, let’s go meet the new guy.”

“But,” he protests, looking at the bagels sitting on the counter longingly. “One probie’s just like the next—”

“And this one isn’t really a probie, which you’d know if you bothered to listen to Chim, oh, ever,” Eddie says, pushing himself up off the couch; when he reaches his hand out, Buck takes it and allows himself to be pulled along, and he just … doesn’t let go of Eddie’s hand for a few extra seconds. “He’s a transfer, somewhere up north, but I don’t remember where.”

“Doesn’t matter,” Buck says, eyes still on the bagels as Eddie pulls him past the counter and finally lets go of his hand. Why’s Eddie so interested in where this guy is from, anyway? “L.A. is the place to be, man—” he’s cut off as Eddie introduces himself to someone coming off the top of the stairs and he sighs, letting his head turn from where he’s counting _exactly_ how many blueberry bagels are left to the guy now shaking Eddie’s hand, and—

Oh.

Oh, _fuck_ , the guy is gorgeous.

“Derek Hale,” the guy—Derek—says, looking uncomfortable—probably at the way Buck’s jaw is on the floor—as he looks past Eddie to him. “Just came from Beacon Hills.”

“Evan Buckley,” he says, holding out his hand. He’s gonna fucking kill Bobby or whoever approved this transfer because Derek Hale is tall, dark, and probably exactly Eddie’s fucking type, and now Buck’s going to watch his best friend fall in love with some idiot rather than him, stand next to him at his wedding as his best man instead of as the groom, and probably have ten babies who would never cry and immediately be put in print ads.

Fuck, fuck, fuck.

“Call him Buck,” Eddie says, giving him a pained look which pretty clearly says _what the fuck are you looking at him like that for you idiot can’t you see I’m in love with him already_ , and Buck yanks his hand away from Derek’s. “Sorry about him, he’s a little preoccupied with food. Has anyone shown you to the locker room?” At Derek’s short shake of his stupidly handsome head, Eddie nods. “Come on, I’ll give you a tour and we’ll find wherever it is that Chim—uh, Captain Han—stalked off to.”

Buck can’t seem to make his feet work as he watches Eddie lead Derek down the stairs, hand fluttering to Derek’s elbow to steer him gently in the direction of the locker room, nodding his chin up as Nathan passes by them.

Even _Nathan_ , happily married to his wife of twelve years, gives Derek an impressed once over, and god, Buck hates himself. He’s had five years to get his life together and convince Eddie that he’s worth tying himself to for the long run as someone other than a best friend, and now he’s lost his chance because Bobby couldn’t approve the transfer of some middle-aged guy who would add another tally mark in the “died of cardiac arrest” category of on-the-job deaths, no. 

It had to be Derek Hale.

Fuck his life, seriously.

He doesn’t realize that he’s wandered over to the railing and is watching Eddie and Derek a little _too_ intensely until Eddie looks up at him and frowns, and Buck jerks backwards, hands flying off the rail like they’ve been burned. It’s fine, he’s fine, he can get through the next twenty-four hours and then—well. He’s not actually sure what he’ll do after that. It’s Wednesday, and he and Eddie usually get breakfast together after their shift before he goes home and crashes for a few hours, because Thursdays are pasta nights and if he knows Eddie, he definitely hasn’t gone grocery shopping yet, so Buck would typically swing by the store while Eddie went to pick up Chris, but—

But maybe Eddie will look at Derek with that soft look he sometimes gives Buck and invite him out for breakfast with them, and as much as Buck wishes that Derek was the biggest idiot on the planet and therefore definitely, absolutely not good enough for Eddie, Bobby’s usually pretty good about hiring people who know what they’re doing, which means Derek’s sadly not just a pretty face. So Derek will tag along to breakfast, because who in their right might would _ever_ turn Eddie down, only it won’t be tagging along because Buck really cannot stomach that, so he’ll make an excuse to head home, and then it’ll just be Derek and Eddie.

Together.

On a date.

Mercifully, the alarm rings. He grabs a bagel—then two more—on his way down and tosses the one coated in salty, greasy cheese to Eddie, chomps the blueberry between his teeth, and chucks the raisin (his least favorite) at Chim’s head, and forgets about Derek.

….accidentally, of course.

“Didn’t know what you liked,” he says, trying to look apologetic after Eddie gives him a look and shakes his head before disappearing into the truck. “Sorry, man.”

Derek doesn’t say anything, just shrugs and takes the seat next to Eddie.

Buck’s seat.

He looks at Eddie, unable to resist the pout he _knows_ is on his lips, and god it’s so childish but he can’t help it, it’s _his seat_ , Eddie is _his friend_ —

“Gonna join us today, Buck?” Chim asks, shoving him none too gently through the door as he swings into the front seat, and Buck bites down a curse as his shin hits the step. 

This day is not going how he planned. 

The day is frustratingly slow, which gives Eddie every chance to _bond_ with Derek, who has probably never broken a rule or had a hair out of place in his life. And maybe, watching Eddie interact with Derek, Buck understands why Eddie is still single because if this is his idea of flirting, it’s pretty pathetic. 

Like when Buck slides into the driver’s seat on the way to a call and has to hop a curb to get around a Miata stopped in the lane like there isn’t twenty-five tons of ladder truck blaring the horn behind it, Chim hits him on the arm and says “stay on the road! Keep clear of the moors!” and Buck’s about to ask what the hell he’s talking about when Derek mutters, barely audible over the headset, “beware the moon, lads,” and Chim cackles. Buck watches him in the mirror for a moment before switching his gaze to Eddie, whose jaw is tense before he clears his throat and asks Derek what kind of movies he likes. 

It’s off-hand, forced casual sounding—until Derek clears his throat and says, “I like sports movies—uh, baseball, mostly.”

Buck desperately wishes he would have said horror movies, because Eddie fucking hates horror movies and is forever bitching about how there’s no creativity in splattering fake blood around a room and having someone jump out with a knife. 

Eddie loves sports movies. 

“Is this heaven?” he says, and Buck looks at him, frowning as the determined set of Eddie’s mouth eases into something more relaxed.

“No, it’s Iowa,” Derek says. He smiles— _smiles_ —and it’s small and pleased and goddamn beautiful, and Buck turns his gaze back to the traffic-packed streets and fights every cell in his body that wants him to clamber into the back seat and punch Derek Hale in his perfect mouth. 

“If you build it, he will come,” Chim adds. 

Buck glances in the mirror again, looks at how they’re both watching him, and shrugs. “Dunno what that one is,” he says, and Eddie rolls his eyes.

He tunes out the rest of their conversation. 

Or like how Eddie hesitates for a moment before sitting down at the table for dinner, looking distinctly uncomfortable when Derek walks past them to sit on the couch—and sure, Buck knows he should invite Derek over, because if Bobby was there instead of Chim (who’s too busy talking on the phone with Maddie to realize that Buck’s already shoving pizza in his mouth—and Chim’s pizza, at that) he would have already said that the 118 eats as a family—but the only chair open is across from Eddie and—

“Derek,” Eddie finally says, “come grab some pizza and sit with us.”

“I brought some food,” Derek says; his eyes flicker across the tabletop, crammed full of pizza boxes (because Bobby’s _not_ here and Buck and Eddie are taking definite advantage of not needing plates for once), then down at the bag in his hand. “But thanks.”

“Kind of a station rule,” Eddie says, and he kicks out the chair across from him with his foot. “We always eat dinner together. Lunch is on your own, but dinner’s a family situation. Gets a little loud, especially with this one here,” he says, pointing at Buck and ducking when Buck picks up what’s left of his water glass and tosses it in Eddie’s face, “but you’ll get used to it.”

Derek only hesitates for another moment before crossing the space between them in a few steps and sinking into the chair, abandoning his packed dinner on the countertop on the way. “I’ve got a few siblings and more cousins than I can count,” he says, reaching for the open box of pepperoni pizza and pulling out a slice, “I think I can handle Buck.”

“I dunno man, I’ve got two sisters and a dozen cousins and I thought I was safe, but Buck here doesn’t know the meaning of volume control—”

“Uh, _hey_ ,” Buck says, because sure it sounds friendly and teasing but Derek doesn’t know him, doesn’t know he’s Eddie’s best friend, doesn’t know how they are, and the last thing he wants is for Derek to _realize_ he’s got a shot with Eddie. Eddie hasn’t been doing the greatest job at flirting, which thank _God_ , there’s only so much Buck can handle, but—

“What the hell,” Chim says, grabbing the slice of barbecue chicken straight out of his hand, “you know I only ordered one of these, don’t take them all, Buckley.”

“Barbecue on pizza is an abomination,” Eddie mutters, shaking his head, and when Derek voices his agreement, Buck manages a tight smile, fakes a stomach ache, and walks away. 

Derek takes the bunk next to Eddie that night. 

Buck doesn’t sleep. 

Okay, so he must sleep, because when he wakes up it’s to Derek clearing his throat at the door. “Captain Han’s making breakfast,” he says, and as Buck is blinking himself awake, Derek looks right at him and adds, “do you ever—you know—why’s his name Chimney instead of like, Solo or something?”

“Huh?” Buck says, intelligently. 

God, no wonder Eddie never bothered to turn his terrible flirting on him. 

“Like Han Solo?”

Buck shrugs. “Is that a baseball player?”

Derek looks at him, eyes wide, and—bursts out laughing. “Good one,” he says, and Buck stares after him as he backs out of the bunk room, chuckling. 

He’s even more gorgeous when he’s laughing, and Buck feels the last chance he might have had with Eddie crumble into ash and float away. 

Derek smiles almost all the way through breakfast. Eddie’s quiet at first, eyes darting towards Buck worriedly, but eventually he stops kicking Buck in the ankle and starts chatting easily with Derek, and he doesn’t glance Buck’s way once as he finishes off his eggs and tosses the last orange on the table to Derek.

By the time they’re sprawled out around the television twenty minutes before shift change, watching Eddie destroy Chim at Mortal Kombat—Buck is relieved when Derek declines, pulling a book out of his bag instead, until Eddie starts asking him about what he’s reading like he’s ever picked up a book for fun in his goddamn life—Buck’s got a pit in his stomach and is trying to figure out a way to get Eddie to agree to go back to his place now that Chim has unknowingly ruined their breakfast plans. 

Before he can blurt out something there’s a sharp whistle from the kitchen, and Buck looks over to see Athena standing there, surveying the mess they’d left. The guy behind her trips over Derek’s abandoned chair—the only one that had been pushed in—says “I’m alright!” as he stands up, and smiles brilliantly at them, pink-cheeked, before running a hand over his buzzcut like he expects to meet hair there. 

Athena sighs like the weight of the world has been placed on her shoulders. “Sit _down_ , Detective Stilinski,” she says; the words sound worn out, like she’s said them all night. “Howard Han,” she continues, “ _this_ is how you leave my husband’s station?”

“Ooh, you’re in trouble,” Buck sing songs, and leans forward to peer around Derek at Chim—which is how he notices that Derek has suddenly stiffened and become still; twenty seconds ago he had been leaning against the back of the couch, eyes on Eddie—now, he’s staring down at his book like it’s personally offended him, spine perfectly aligned as he sits straight up. 

Weird. 

Athena continues to berate Chim as her—partner? Buck didn’t think she _did_ partners—does what he must think is a casual saunter over towards the couch before he plops inelegantly onto the arm next to Derek. “Nice place,” he says brightly.

“Thanks,” Derek says. His jaw is clenched; he doesn’t respond at all when the detective wiggles his eyebrows at him before turning his gaze towards Buck and planting a hand on Derek’s shoulder as he leans over with his other hand stuck out. 

“Stiles,” he says, beaming. He leans over too far and nearly falls into to Derek’s lap and Buck watches, fascinated, as Derek’s hands shoot out to steady him, holding him still as Stiles shakes Buck’s hand, pushing him gently up after. His cheeks are flushed, despite the tense line of his body, his eyes dart towards Stiles and around the room before returning to his book. 

“Buck,” Athena snaps, like Buck must have missed the first few times she called his name while he was are considering Derek and the way he reacted to Stiles, standoffish and gentle at the same time, shoulder still leaning against Stiles’ arm, the corners of his mouth more relaxed, like—like he’s attracted to him, looks like Buck feels around Eddie, and instead of the relief Buck had assumed he would feel, he just feels—

“Buck!”

“Sorry,” he mutters, heading towards the kitchen, glancing at Eddie’s triumphant face as Chim’s character falls. 

Eddie’s going to be heartbroken, and Buck feels like shit about it. 

Fuck. 

God damn it, he’s going to hate himself, but when Derek opens the dishwasher beside him and starts handing him plates, he bites back a sigh. “Eddie’s a really good guy,” he says, trying not to stack the plates with more force than necessary. They’re already down two—turns out Bobby was right when he’d told Buck and Eddie not to slide plates along the length of the island—and he’s not trying to break any more. 

“He seems like a good friend to have,” Derek says after a moment, glancing up at him. 

“He’s pretty perfect,” Buck says, because it’s not like it’s hard to talk about how great Eddie is, how he makes Buck feel like the center of the universe whenever they’re alone together, the way he loves Chris with his whole heart, the way he treats people out on calls with respect that they often—in Buck’s opinion—don’t deserve. “Give him a chance and he’ll give you everything he has, you know? He’s that shirt off your back type once you get close.”

Derek opens his mouth, but before he responds, Stiles wedges his way between them, hopping up on the counter as soon as Buck closes the dishwasher. “So,” he says—he’s got very excitable eyebrows, Buck thinks, wagging them at Derek, shooting them up as he looks around the room—“any big fires? Dangerous rescues? Getting half-naked and discussing which one of you should be in the annual LAFD calendar? Anything good for dinner?”

“We had pizza for dinner,” Derek says mildly, and his lips twitch when Stiles frowns. “Family style.”

“That doesn’t answer the question about the calendar,” Stiles says after a moment, and he looks over at Buck. “I bet it’d be you, you’re all Abercrombie & American, unlike tall, dark, and moody over here—”

Buck laughs and a moment later Stiles tumbles to the floor, laughing as he goes, completely unbothered by the fact that Derek has just pushed him off the countertop. He flips Derek off and walks away with his hands shoved in his pockets, bounce in his step as he makes his way back towards Athena, and—well, if _that’s_ Derek’s type, Eddie probably doesn’t have a chance, but Buck could still try. 

If you love them set them free and all that bullshit. 

He tries to think of what to say while he wipes the counters down and tosses the rest of the dirty dishes in the sink—someone else can finish up, he’s not the only one who made the mess—and when he goes to rejoin the group, he almost looks past the way Derek’s standing behind Stiles, leaning slightly into his space— _almost_ , but he doesn’t, so he stops a few feet away and shamelessly listens in. 

“I told you I didn’t need checking up on,” Derek says, and Stiles immediately protests, gesturing towards Athena. 

“I’m here because she’s here, boo, save the panty-twisting for when we’re at home and I can enjoy it.”

“You won’t be enjoying anything—”

“Oh, yeah, you say that _now_ ,” Stiles says, and he reaches back without looking and pats Derek’s cheek. “I can’t believe you ate pizza. I packed you _lunch_ , Derek, I worked hard on that—”

“You put a Lunchable in a bag—”

“There was also a turkey sandwich, asshole, see if I do anything for you again—”

There’s a quick scuffle; Stiles elbows Derek but Derek catches his wrist and pulls him back into a brief hug, and something about the way his body curves into Stiles tells Buck that this is not new, this isn’t roommates or friends or—

This is what he wants—what he _almost_ has—with Eddie. 

So he’s going to tell Eddie about Derek and Stiles … any time now. He’s actually a little surprised that Eddie hasn’t brought it up yet; when he’d met Ana he’d kept it to himself for approximately ten seconds before blurting it out and bitching when Buck made fun of him for his spectacular crash and burn. But they’ve been sitting at the cafe—coffee instead of breakfast this morning, because both of them are creatures of routine and because there will never be a day that Buck turns down a chance to spend more time with Eddie—but they’ve been here for nearly an hour and Eddie’s still trying to explain the finer points of—

Well, Buck isn’t really sure. He hasn’t really been paying attention, his mind is too busy working out the best way to comfort Eddie when he hears the news, trying to figure out whether Eddie’s jaw will clench and he’ll do that thing where he runs his tongue under his lips or if maybe his eyes will get shiny and sad—“Derek and Stiles are together,” he blurts out, letting the spoon he had been playing with clatter to the table. 

Eddie stops and looks at him, brow furrowed. “I—yeah? Kinda figured after he said he had a husband named Stiles and then one showed up?”

“He—“ Buck pauses. He definitely does not remember Derek saying he had a husband, but then he’d spent a significant amount of the day decidedly not pouting in the gym while everyone else hung out upstairs. He looks carefully at Eddie, traces the lines of his face and frowns. “How do you feel about that?”

“How do _I_ feel? You were the one staring at him the entire shift—”

“I was trying to, you know, size him up for you—”

Eddie chokes on the coffee he’d just taken a drink of, a flush settling high on his cheeks. “For _me_?”

God, he’s in love with a moron. “Yes, for you,” he says with patience he doesn’t feel, trying not to sound like his heart is getting ripped out of his chest. “The way you looked at him when he walked up the stairs—”

Eddie, the asshole, starts laughing. “Buck,” he says, “Jesus, just admit you like the guy. You couldn’t take your eyes off him, you did the pouting routine whenever I talked to him, you spent the whole time going between ignoring him or antagonizing him like you did with—”

Eddie stops laughing abruptly and stares at him and Buck glares, because _fine_ , he can’t exactly protest that he ignored Derek but other than not giving him a bagel—and hiding his book—he wasn’t antagonizing. He was trying to be nice, but the idea of some dick just sweeping in and taking Eddie _away from him_ sat wrong with him and it’s not his fault that he didn’t hear the guy was married. “Like I did with who,” he says, rolling his eyes and trying to think back to their few probies. He’s not even sure—

“With me,” Eddie says.

Buck stills. “Uh,” he says. “I—”

He doesn’t— _can’t_ —say anything, has no idea what to say; every time he’s thought about this he’s been a lot … smoother. Not so jealous. This is just wrong, Jesus, this is never going to work out in his favor, Eddie’s going to get up and walk away—

“So do we need to go get you something a little harder to get you over this guy,” Eddie says, nodding at Buck’s coffee cup, “or do I still have a shot?”

He’s going to pass out. “A shot?” he asks, and his voice definitely does not get higher, no, he’s perfectly calm, very cool, not at all shoving his hands under his thighs so Eddie can’t see how they’re shaking. “I—but Derek—you—”

“Whatever you thought about me was all in your head, Buck,” Eddie says. “I thought _you_ liked him and I was trying to be supportive but it—it sucked, okay? I hated how you looked at him and I sure as fuck hope I’m not wrong about this because you still haven’t said anything—”

“I’m in love with you,” Buck says, too loud and too fast, but Eddie smiles at him from across the table and he reaches out and grabs for Buck’s hand, squeezing. “I’m in love with you,” he says, more quietly this time, holding Eddie’s gaze. 

“Thank God,” Eddie says, the corner of his mouth lifting up. “Because Derek’s built like a tank, man, I really didn’t want to have to try to fight him for you.”

**Author's Note:**

> tumblr @ [elisela](http://elisela.tumblr.com)


End file.
